I'm finding the ongoing saga of XMarks pretty interesting.  In short, they sent out a going-out-of-business announcement, enjoyed a significant and sustained level of protest from satisfied customers (tens of thousands of whom even pledged to start paying annually for the free service), and apparently attracted enough investment interest to stay alive.  As a happy consumer of their bookmark syncing service for years, I was surprised at their announcement of closure, and I'd love to see them make it.  Their software simply works better than Firefox Sync, which has become less buggy over time, but still manages to bug me (by, for instance, forcing me to open to the same default tabs on my home and work machines).  Best of luck to the Xmarks folks!